False positive reporting

In this PT the method detection limit (MDL) was an important performance indicator. The participants were asked to report the MDL estimated through method validation.

From the technical information provided by the laboratories, it can be observed that there is no harmonised method for MDL estimation amongst Member States laboratories which could lead to inappropriate comparison of MDL estimated in different laboratories. The summary of the reported MDL and the used procedure to derive the MDL is shown in Table 6.

It can be noticed that 21 laboratories (group C, Table 3) reported false positive for the blank

sample 05, this might indicate that the MDL was not appropriately estimated, or the method

validation for such a matrix was not yet performed.

TABLE 2. AVERAGE PERFORMANCE SCORE AGAINST THE USED

Alpha spectrometry 88 76

Liquid scintillation 11 69

Proportional counter 5 56

Gross alpha counter 2 75

ZnS counter 2 10

Not reported 6 -

TABLE 3. LABORATORIES GROUPING RELATED TO THE CATEGORY OF

RECOMMENDATIONS

TAB

LE 4. SUMMARY INFORMAT IO N ON T H E ANA LYT ICA L PROC EDURE AS REPORTED BY TH E PART IC IPA NTS IS PRESENTED AGA INS T THE AVERAGE SCO RE, WHERE NUMBER OF ‘A ’ WAS MU LT IP LI ED B Y 20, ‘W’ BY 10. NR: NOT REPORTED

Lab. Sample Source preparation Measurement technique Average score 1 Evaporation Auto deposition Alpha spec. 100 2 Evaporation Auto deposition Alpha spec. 90 3 Evaporation Auto deposition Alpha spec. 80 4 Evaporation Auto deposition Alpha spec. 70 5 Evaporation Auto deposition Alpha spec. 100 6 Chelation Electro deposition ZnS counter 20 7 Evaporation Auto deposition Alpha spec. 100 8 Evaporation Auto deposition Alpha spec. 90 9 Evaporation Auto deposition Alpha spec. 80 12 Evaporation Auto deposition Alpha spec. 100 13 Evaporation Auto deposition ZnS counter 0 14 Evaporation Auto deposition Alpha spec. 70 15 Evaporation Auto deposition Alpha spec. 90 16 Evaporation Auto deposition Alpha spec. 90 17 Deposition Deposition Liquid scintillation counter 60 18 Evaporation Auto deposition Alpha spec. 80 19 Evaporation Auto deposition NR 90 20 Evaporation Auto deposition Alpha spec. 0 21 Evaporation Auto deposition Alpha spec. 80 22 Evaporation Auto deposition Alpha spec. 30 23 NR NR NR 0 24 Evaporation Auto deposition Alpha spec. 90

Lab. Sample Source preparation Measurement technique Average score 25 Evaporation Auto deposition Alpha spec. 100 26 Evaporation Auto deposition Alpha spec. 100 27 Evaporation Auto deposition Alpha spec. 100 28 NR NR Liquid scintillation counter 60 29 Evaporation Auto deposition Alpha spec. 30 30 Evaporation Auto deposition Alpha spec. 50 31 Evaporation Auto deposition Alpha spec. 60 33 Evaporation Auto deposition Alpha spec. 100 34 Evaporation Auto deposition Alpha spec. 100 35 Evaporation Auto deposition NR 90 36 NR NR Liquid scintillation counter 0 37 Evaporation Auto deposition Alpha spec. 60 38 Evaporation Auto deposition Alpha spec. 100 39 Evaporation Auto deposition Alpha spec. 100 40 Evaporation Auto deposition Alpha spec. 80 41 Chelation Electro deposition Proportional counter 50 42 Coprecipitation Coprecipitation Proportional counter 90 43 NR NR NR 100 44 Scintillation cocktail Scintillation cocktail Liquid scintillation counter 10 46 Evaporation Auto deposition Alpha spec. 100 47 NR NR Liquid scintillation counter 100 49 None None Alpha spec. 20 50 Evaporation Auto deposition Alpha spec. 100 51 Evaporation Auto deposition Alpha spec. 100 52 Evaporation Auto deposition Alpha spec. 50 54 Evaporation Auto deposition Alpha spec. 20

12

Lab. Sample Source preparation Measurement technique Average score 55 NR NR Liquid scintillation counter 90 56 Evaporation Auto deposition Alpha spec. 90 57 Evaporation Auto deposition Gross Alpha counting 70 58 NR NR NR 80 59 Evaporation Auto deposition Gross Alpha counting 80 60 NR NR Liquid scintillation counter 60 62 Evaporationn Auto deposition Alpha spec. 60 63 Evaporation Auto deposition Alpha spec. 70 64 Evaporation Auto deposition Alpha spec. 90 65 Evaporation Auto deposition Alpha spec. 100 67 Evaporation Auto deposition Alpha spec. 100 69 NR NR Alpha spec. 80 70 Evaporation Auto deposition Alpha spec. 20 71 Evaporation Auto deposition Alpha spec. 100 72 Evaporation Auto deposition Alpha spec. 90 73 Evaporation Auto deposition Alpha spec. 80 74 Evaporation Auto deposition Alpha spec. 100 76 Evaporation Auto deposition Alpha spec. 100 77 NR NR Alpha spec. 10 78 NR NR Liquid scintillation counter 100 79 Evaporation Auto deposition Alpha spec. 100 80 Chelation Electro deposition Alpha spec. 0 81 Evaporation Auto deposition Alpha spec. 100 82 Evaporation Auto deposition Alpha spec. 20 83 Evaporation Auto deposition Alpha spec. 100 84 Evaporation Auto deposition Alpha spec. 100

Lab. Sample Source preparation Measurement technique Average score 85 LSC LSC Liquid scintillation counter 100 86 Evaporation Auto deposition Proportional Counter 20 87 Evaporation Auto deposition Alpha spec. 60 88 Evaporation Auto deposition Alpha spec. 60 89 Evaporation Auto deposition Alpha spec. 90 90 NR FALSE Proportional Counter 40 91 Evaporation Auto deposition Alpha spec. 90 92 Evaporation Auto deposition Alpha spec. 100 93 Filtration Filtration Liquid scintillation counter 80 94 LSC LSC Liquid scintillation counter 100 95 Evaporation Auto deposition Alpha spec. 20 96 Evaporation Auto deposition Alpha spec. 100 97 Evaporation Auto deposition Alpha spec. 70 98 Evaporation Auto deposition Alpha spec. 60 99 Evaporation Auto deposition Alpha spec. 0 100 Chelation Electro deposition Alpha spec. 30 101 Evaporation Auto deposition Alpha spec. 40 102 Evaporation Auto deposition Alpha spec. 60 103 Evaporation Auto deposition Alpha spec. 100 104 Evaporation Auto deposition Alpha spec. 80 105 Evaporation Auto deposition Alpha spec. 100 106 Evaporation Auto deposition Alpha spec. 100 107 Chelation Electro deposition Alpha spec. 100 108 Evaporation Auto deposition Alpha spec. 100 109 Chelation Electro deposition Alpha spec. 100 110 Evaporation Auto deposition Alpha spec. 80

14

Lab. Sample Source preparation Measurement technique Average score 112 Evaporation Auto deposition Alpha spec. 100 114 Evaporation Auto deposition Proportional Counter 80 115 Chelation Electro deposition Alpha spec. 100 116 Evaporation Auto deposition Alpha spec. 40 117 Evaporation Auto deposition Alpha spec. 100 118 Evaporation Auto deposition Alpha spec. 40 119 Chelation Electro deposition Alpha spec. 100 120 Evaporation Auto deposition Alpha spec. 20 121 Evaporation Auto deposition Alpha spec. 90 123 Evaporation Auto deposition NR 100 124 NR NR Alpha spec. 80 125 Evaporation Auto deposition Alpha spec. 80 126 Deposition Deposition Alpha spec. 100 127 Evaporation Auto deposition Alpha spec. 80

TAB LE 5. Po-210 A NA LYT IC A L PROCESS P ARAMETERS AS REP ORTED BY T HE PARTI C IPANTS. NR: NOT R EPORTED

Lab code

Sample mass [g]

Counting time [s]

Gross counts Counting efficiency [%] Tracer added activity [Bq] Unc. of added Tracer Tracer recovery [%] 1 5.023 79711 6314 26 0.31 0.016 100 2 26.63 60000 16566 22.4 0.1738 0.0087 96.8 3 8.113 90000 4383 12.8 0.2 0.0009 87.3 4 74.3 81759 26519 9.6 0.0792 0.0034 93.1 5 30.35 11820 1618 18.8 1.48 0.01 45.8 6 60.15 7200 929 16 NR NR 63 7 20.75 55402 10409 17.6 0.202 0.0051 98 8 10.1429 60000 6467 27.4 0.397 0.0012 78.6 9 1.0348 246228 2646 24 0.036 0.002 80 12 2 61000 1420 29 0.1 0.005 73 13 20.6448 30000 10760 52 0 0 93 14 25.95 60000 9044 16.58 0.6262 0.0188 69.25 15 15.347 60000 6448 25 0.96 0.01 60.9 16 5.0788 102477 6793 NR 0.193 0.0028 NR 17 26.77 7200 2553 50 NR NR NR 18 10 5000 683 0.32 NR NR NR 19 16.8 8000 1067 23 0.24 0.02 63 20 2.0526 64829 924 29.72 0.136 0.002 46 21 5.0812 30301 630 10.91 0.5717 0.0286 74.43 22 31.60977 10000 2994 25 0 0 0 23 3.1394 17220 355 28.63 0.134 0.002 45 24 2.725 92605 2618 19 0.039 0.001 95 25 57.5844 59653 40413 26 12.456 0.029 87

16

Lab code

Sample mass [g]

Counting time [s]

Gross counts Counting efficiency [%] Tracer added activity [Bq] Unc. of added Tracer Tracer recovery [%] 26 0.5041 84272 519 28.92 0.0105 0.00105 60.86 27 20 60000 NR 18.2 0.32 0.006 49.3 28 10 5400 NR 85 NR NR NR 29 21.0891 228910 40753 0.0353 0.00001 30 19.68 15000 2191 34 1.858 0.013 36.5 31 10.392 50000 4811 21 0.861 0.0018 90.2 33 4.1578 200000 37.9 0.043 0.0004 34 13.8 160000 11200 14.5 2.2 0.02 70.2 35 5.1858 86405 4914 27 0.08 0.001 83 36 5 6000 370 57 NR NR NR 37 3.089 24583 1715 36.67 0.0696 0.0003 83.31 38 4.1065 48540 2050 29.1 0.163 0.005 76.6 39 10.35 10800 1131 37.2 NR NR 96 40 19.9193 10690 2044 19.89 NR NR 95.15 41 55.41 20400 7625 36.6 0 0 73.7 42 29.74 216000 86962 31.33 0.0387 0.001 100 43 1.0459 398098 2191 20 0.089 0.0015 53 44 0.25 12000 4324 57 NR NR NR 46 3.0928 75161 2197 23.28 0.03149 0.00013 65.15 47 4.2 24900 5769 99.5 0 0 0 49 51.9497 1800 231 38.073 0 0 0 50 99.6218 13608 649 26.59 0.423 0.0145 95 51 10.381 107000 20.6 NR NR NR 52 26.64 8000 984 20 NR NR NR

Lab code

Sample mass [g]

Counting time [s]

Gross counts Counting efficiency [%] Tracer added activity [Bq] Unc. of added Tracer Tracer recovery [%] 53 50 78820 699 27.9 0.57 0.01 15.4 54 5.1885 21600 1190 0.4404 0.0048 54.8 55 15.5 28440 15642 71.1 NR NR NR 56 10 21200 2452 25 0.0511 0.00025 87 57 50.2562 500 494 32.94 0 NR NR 58 15 74495 NR NR NR NR NR 59 10 400000 1195 17.3 NR NR NR 60 4 15000 3189 86.7 NR NR NR 62 20.07 80000 10382 17.52 6.03 0.12 76.1 63 21.06 55177 8813 25.42 3.66 0.05 75 64 53.3781 33000 10650 14 0.17 0.0017 83 65 47.1712 9154 5086 36.3 0.534 0.027 68.94 66 69.01 86404 12657 9 13.2865 0.0279 50.6 67 5.199 82800 3783 NR 7.39 0.22 91 69 NR 70 20.09 84417 11730 19.4 0.065766 0.002 62.1 71 2.6095 252812 9338 29.95 0.050289 0.001106 99.9 72 5.17 85000 1735 14.8 0.523 1.7 54.2 73 2.07 200000 3692 23 0.02 0.0006 75.3 74 8.31 57600 5395 25.5 0.0542 0.0011 91 76 19.4066 334800 47474 25 0.923 0.02 61.5 77 0.005 323300 361 2.48 0 78 8.1709 29344 13860 100 79 22.7 60000 15360 23.6 0.0813 0.002

18

Lab code

Sample mass [g]

Counting time [s]

Gross counts Counting efficiency [%] Tracer added activity [Bq] Unc. of added Tracer Tracer recovery [%] 80 10.4181 246612 11610 11.92 0.437 0.004 51.27 81 31.509 170000 30740 20.6 0.2002 0.0005 57 82 32.47 18327 3560 20 0.047 0.001 76 83 10.37 36000 5566 36.8 0.1935 0.0097 79 84 1 75600 838 38.9386 0.0774 0.0031 56.227 85 3.63 18000 7449 98 NR NR NR 86 NR 87 25.036 150000 30022 13.9 0.163 0.003 124 88 20 81315 12787 29.83 0.160333 59.8 89 8.1675 23000 1595 16.3 0.2599 0.002 16.3 90 0.94 3600 90 0.503 0 0 0 91 19.85 120000 36696 31.17 0.08758 0.00036786 96.67 92 5 70000 2139 0.169 0.003 93 10.48 2500 1319 85.1 NR 94 NR 95 20.6842 7200 2036 41 0.473 0.015 75 96 5.2108 200000 9497 25.7 0.229 0.0033 68.3 97 5.305 60000 2734 29.9 6.901 0.015 61.38 98 14.98 5800 426 36 0 0 43 99 5 70023 2284 40 0.074 0.004 21.5 100 2.01633 144693 3366 23.33 0.0525 0.0016 80.51 101 20 78994 6127 20.6 0.236 0.0127 16.156 102 70.44 20000 26901 47.2 0.1 0.0013 88.7 103 15.56 21650 835 6.27 0.556 0.011 82.5

Lab code

Sample mass [g]

Counting time [s]

Gross counts Counting efficiency [%] Tracer added activity [Bq] Unc. of added Tracer Tracer recovery [%] 104 60.8 86475 18932 11.1 0.156 0.019 68.2 105 25 200000 56412 25 1.07 0.05 51 106 25.0004 86400 14347 16.85 0.071 0.002 70.4 107 10.0104 82 5665 NR 0.035 0.000035 108 19.71318 84370 5891 24 2.61329 0.0261329 29 109 10.328 80007 9814 26.3 0.1964 0.0023 88.2 110 21 79847 19773 15.65 0.5 0.035 68.6 112 14.7 43200 5005 25 0.89 NR 62 114 50 900 665 27 NR 115 2.5622 252844 2656 NR 0.0816 0.0016 116 2 242322 4842 23 0.077 0.002 95 117 0.982 80000 1749 45 0.123 0.00074 101 118 5.177 251004 4453 NR 0.1129 0.0063 119 30.5346 149048 NR 8.66 7.2 0.3 8.66 120 2.062 55000 1114 26 0.124 0.012 102 121 57.3374 6000 4653 40.6 0.36 0.004 68.88 123 5.2 43200 1182 NR 0.403 0.002 10.7 124 8.214 151200 9179 17.2 0.261 0.8 17.2 125 2.58 60000 1608 28 0.09 0.00018 85 126 3.0314 183605 6730 25 0.1205 0.0025 98 127 25.022 38447 12296 26.9 2.0265 0.009727 86.386

20

TAB LE 6. INF ORMAT ION AS REPORTED BY THE PART IC IPAN TS RE LATE D TO THE ME THOD DETECT IO N LI M IT (MD L) O F PO- 210

Lab code Method validated Reported procedure for Method Detection Limit estimation in the participants laboratories Blank sample score 1 no NR A 2 yes Minimum detection limit (MDL) = 0.06Bq/kg, Repeatability = 0.64 at 10.3Bq/kg A 3 yes Reproducibility : analysis on SRM (f.e. IAEA 134 + 368), one intercomparison test, Repeatability on spiked water samples (variation coefficient of 5.3% with uncertainty of 15%) N 4 yes Detection Limit (MDL) calculated according to ISO-11929 standard, MDL= 0.013 Bq/Kg (99%) (Confidence level) A 5 no For a 1000 minute count the MDL= 0.01Bq/kg A 6 yes Documents and records were first set to meet trackability and traceability requirements, where internal quality control mechanismshave been adopted. Methods stability was checked bymeans of Z-score control charts. Internal method validation parameters including method detection limits, repeatability limits, reproducibility limits, recovery coefficient and relative error were estimated. External method validation has been achieved by participating in national inter-laboratory exercises and international intercomparison exercises and proficiency tests.

A 7 no detection limit: 0.01 - 0.06 Bq/kg A 8 no NR A 9 yes Minimum detection limit: ranges between 0.2-0.4 mBq depending on the camera used. N 12 yes All 5 samples analysed first based on 20 mL aliquots with DL's below 0.1 Bq/kg. Analyses of samples 1-4 repeated based on 2-3 mL aliquots to match spike amounts. A 13 no NR N 14 yes MDL: 0.04 Bq/kg (Po-210) A 15 no We do not routinely analyse for Po-210. We have performed limited cross-checking with other laboratories. A

Lab code Method validated Reported procedure for Method Detection Limit estimation in the participants laboratories Blank sample score 16 no NR A 17 no NR N 18 yes MDL is 0.001 Bq/sample - 19 yes Minimum Detection Limit : 0.04 Bq/kg, Repeatability: 5%, Reproducibility: 8% A 20 no NR N 21 no NR - 22 yes a) Spectrometric system is checked by counting tracer (Pu-242) for MDL level concentration. b) Background count rate fro reproducibility A 23 NR N 24 yes MDL is about 1 mBq for about 24 h counting time A 25 yes Method was validated against SRM4337 (Pb-210 standard that is equilibrium with Po-210 standard) A 26 no NR A 27 no NR A 28 yes ROI 40-400 keV, statistics of single measurement ±5%, statistics of 3 repetitive measurements for result A 29 yes NR A 30 no NR N 31 yes Minimum detection limit was calculated by L. A. Currie's equation. The MDL is 0.07 Bq/kg. Repeatability was not tested. Each sample was counted once by alpha spectrometer. Reproducibility was tested. The identical sample was measured three times. The RSD of results is less than 1.5%. A

22

Lab code Method validated Reported procedure for Method Detection Limit estimation in the participants laboratories Blank sample score 33 yes MDL = < 0.05 Bq/kg A 34 yes MDL = < 0.05 Bq/kg A 35 no NR A 36 MDL = 0.65 +/- 0.16 Bq/kg, Repeatability limit = 0.88 Bq/kg. No reproducibility limits are available at this time. Minimum detectable activity is determined by applying the average of eight replicate analysis of a blank sample to the Currie formula. Repeatability is determined using eight replicate analysis of a NIST traceable reference material. Similar reference materials are used to determine four point linearity.

A 37 yes Minimum Detection Limit = 0.002 Bq/L, Standard deviation of the mean = 13%, Bias = 1,4 % A 38 yes MDL is dependant on sample mass. For low level work where 100g of sample is taken the MDL is 0.005Bq/kg.For these IAEA samples where the activity was very high 4 g of sample was used to achieve an MDL around 0.1Bq/kg, Repeatability at k=2 is 4.2% A 39 yes For this PT MDL=0.15Bq/kg, at Counting Time 25200s, sample Mass 10.4g, Counting Efficiency 37.2%, Recovery 96% (for low salinity waters) A 40 no Although we did not participate yet in a Po-210 intercomparison exercise, we have calculated our Minimum detection limit: for 20 grams of sample, 3 hours of measuring time, efficiency 0,4 and chemical yield 0,95= 0,08 Bq/Kg - 41 yes Minimum detection activity MDL: 0.0123 Bq on TENNELEC S5HP / Gas flow type proportional counter , 36000 sec. counting time ; Minimum detection activity: 0.0062 Bq on TENNELEC TC 257/IPA Silicon detector, SCA counting mode, 60000 sec Counting time . A 42 no NR A 44 no NR A 46 yes 1-MDL=0.00481Bq/L, 2-Triplicate samples analysed, 3-Above 95%. A 47 no NR A

Lab code Method validated Reported procedure for Method Detection Limit estimation in the participants laboratories Blank sample score 49 yes Minimum Detection Limit: 0.31 Bq/kg, Repeatability limit: 0.15%, Reproducibility limit: 0.25% A 50 yes Minimum detection limit: 0.1 Bq/kg A 51 yes Not especially for Po-210, Validation parameters. A 52 no NR A 54 no Method validation for polonium in solid, water and urine samples are in progress. A 55 yes Testing of reproducibility with certified standard A 56 yes The validation method was carried out for urine sample and is believed to be valid for water sample as well, Minimum detection limit: 1 mBq/L when 500 ml of urine is introduced in the analysis, repeatability: 10% at the 20 mBq/L level of activity. A 57 yes Minimum Detection Limit for Sample Code 1 to 4 - 0.2 Bq/Kg(3 sigma). Repeatability ±3%, Reproducibility ±4% A 58 no NR A 59 no NR N 60 yes

The detection limit for Po-210 detection in water samples was calculated by the following formula: DL=3*sqrt(Cb)/(T*E*M) where DL is the detection limit, Cb is the background counts, T is the background counting time, E is the efficiency of detecting alpha particles and M is the sample mass. For Cb=3000 counts, T=300000sec, E=0.867 and M=4g the detection limit is DL=0.16 Bq/Kg. If a water sample of 7g is used the detection limit is reduced to 0.08 Bq/Kg. The repeatability limit was calculated by using the formula R=1.96*sqrt(2)*S where S is the standard deviation of activity A calculated by repeated measurements of each sample (4 measurements for each sample). Repeatability Limits in Bq/Kg were calculated for each sample and were found:sample#1: 3.5, sample#2: 5.4, sample#3: 8.0, sample#4: 8.8, sample#5:1.2.

A

24

Lab code Method validated Reported procedure for Method Detection Limit estimation in the participants laboratories Blank sample score 62 yes In order to determine any bias, the method validation procedure was carried out via the analysis of a standard Po-210 solution supplied in National Metrological Institute, with identical sample counting geometry and detector configuration. For the purposes of this exercise, the minimum detection limit achieved for this methodology was 0.34 mBq/kg (95% confidence level).The repeatability limit was 3%.

N 63 yes NR A 64 no NR A 65 yes MDL=0.01 Bq/kg, repeatability = 6% A 67 yes MDC 0.1 Bq/kg for 5g sample and 23 hour counting time. A 69 no NR A 70 no NR A 71 yes

Genie 2000 software validated by CANBERRA The method validation was performed by analysing IAEA-326 Soil and IAEA-315 Sediment. The obtained data were all in good agreement with the recommended values. The obtained precision (relative standard deviations) is < 10% and the accuracy (relative bias) is < 2%. The minimum detection limit for 5 kg of water sample is 0.016 mBq/kg and the corresponding value for 2.5 g of water 32 mBq/kg.

A 72 yes I could give the validation parameters for these matrices. Furthermore, the minimum detection limit highly depends on the processed sample volume. Again there is no sense in giving a detection limit as such. A water sample is much simpler than a silicon-containing sample with a strongly oxidizing chemical treatment. A 73 yes The method validation was performed on urine samples of 500 ml. Considering a counting time of 200000s the validation parameters were: Minimum detection limit: 5 mBq/l; Repeatability limit : 5%; Reproducibility limit : 9%. N 74 no NR A

Lab code Method validated Reported procedure for Method Detection Limit estimation in the participants laboratories Blank sample score 76 yes Detection limit (MDL): 0.005 bq/kg, Repeatability limit: 1.4 bq/kg for sample of 50 bq/kg radioactivity, at 95% confidence level. Reproducibility limit: No data A 77 no NR A 78 no NR A 79 yes MDL 0.1 Bq/kg, reproducibility limit 10% A 80 yes Validation was performed as emergency method; MDL: 0.16 Bq/kg. N 81 no NR A 82 no NR A 83 no NR A 84 yes 1 pCi/L MDL, 20% precision limit, 25% bias limit N 85 no NR N 86 no NR A 87 yes Limit of detection (MDL) 0.05 Bq/kg, Repeatability 0.6% A 88 yes MDL = 6.225E-04 Bq/sample, LCS = Found-to-Added 98%A 89 no NR A 90 no MDL = 0.0089 Bq A 91 yes Water samples were spiked with a NIST traceable standard at 4.92, 11.5, 26.3, 42.6, 82.2, 392, and 755 mBq/L. The %recoveries ranged from 91% to 112%. The relative percent difference ranged from 3.5% to 12%. The typical MDL values for samples analyzed in this study ranged from 0.00477 to 0.09648 Bq/kg. A

26

Lab code Method validated Reported procedure for Method Detection Limit estimation in the participants laboratories Blank sample score 92 no NR A 93 yes MDL 0.3 Bq/l N 94 yes NR A 95 no NR N 96 no The Currie detection limits ranged over 0.09 to 0.17Bq/kg for these particular samples A 97 no NR A 98 yes The MDL for our procedure is less than 0,05 Bq/Kg. The reproducibility parameter is 0,95. N 99 yes Minimum detection limit: 0.08 Bq/kg, Repeatability limit: smaller than 8%, Reproducibility limit: smaller then 10% N 100 yes MDL: 0.02. Use two different method to check reproductively. A 101 no NR N 102 no NR A 103 yes MDL: 0.05 Bq/kg A 104 no NR A 105 yes MDL is 0.05 Bq/kg A 106 yes MDL=0.04 Bq/kg where efficiency=0.2; yield=0.6; sample mass=25g, counting time=86400s. Accuracy: 15%. Precision: 10% (12 samples on day of analyses). Reproducibility: 13% (more than 50 test samples analysed over a year as test control samples) A 107 no NR A

Lab code Method validated Reported procedure for Method Detection Limit estimation in the participants laboratories Blank sample score 108 no Based on peer reviewed publication A 109 no Minimum detection limit (MDL):12 counts/measuring sample A 110 yes Minim detection limit: 0.5Bq/sample in about 24hours (95% confidence level) Repeatability: 5%. Reproducibility: 7% N 112 no NR A 114 no MDL: 0.004 Bq/ml. Reproducibility: 0.95 N 115 no NR A 116 yes Minimum detection limit, Repeatability limit, Reproducibility limit. A 117 yes NR A 118 no NR N 119 no NR A 120 yes Reagent blank (triplicates) was spiked with the same amount of tracer (Po-209). MDA was determined to be 0.084 Bq/Kg. A 121 yes The detection limit (MDL) for a 1 gram solid sample is 0.005Bq/g. Note, the detection limit will vary depending on the sample weight. Historically, the method has yielded a precision (relative standard deviation) of +/- 10%. The method has yielded an accuracy [Average Recovery (%) ± standard deviation (%)] of 99.0 ± 9.1 A 122 NR NR A 123 yes MDL=0.007Bq/kg. Repeatability limit: r=2.8*S, #1: 2.7; #2: 7.6; #3: 3.9; #4: 8.0; #5: 0.093 Bq/kg, S was used as Standard deviation of 4 analyses. A 124 no NR A

28

Lab code Method validated Reported procedure for Method Detection Limit estimation in the participants laboratories Blank sample score 125 no NR A 126 yes Repeated analysis on all samples. Note! reported values denote arithmetic means A 127 yes MDL: 3.00E-02 Bq/g. Accuracy : u=2.41. Precision: 6.41%-

Dans le document Worldwide Open Proficiency Test IAEA-CU-2007-09: A-Determination of PO-210 in Water | IAEA (Page 18-39)